Apparatus for filtering gases

ABSTRACT

In an apparatus for filtering gases with a closed container which is divided by a horizontal perforated plate into a lower compartment provided with a gas inlet and an upper compartment provided with a gas outlet, and with tubular or candle-shaped filter elements which are sealingly suspended in holes of the perforated plate and are supported by a flange-type enlargement at their upper end on the perforated plate, in order to also ensure reliable sealing during swivel motion of the filter elements relative to the perforated plate, it is proposed that the flangetype enlargement form a bearing surface which lies on the surface of a sphere with center point above the bearing surface and on the vertical center axis of the filter element, and that the hole in the perforated plate so surround at a distance the filter shell of the filter element downwardly adjoining the enlargement that the filter element can swivel over a certain angular range about the center point of the sphere.

The invention relates to an apparatus for filtering gases with a closedcontainer which is divided by a horizontal perforated plate into a lowercompartment provided with a gas inlet and an upper compartment providedwith a gas outlet, and with tubular or candle-shaped filter elementswhich are sealingly suspended in holes of the perforated plate and aresupported by a flange-type enlargement at their upper end on theperforated plate.

Apparatus of this kind are used, for example, to filter hot gases whichresult from coal gasification. The gas to be filtered flows underpositive pressure from the outside to the inside through the filterelements, and in known apparatus a very large number of such filterelements are suspended parallel to one another in the perforated plate.On account of local pressure fluctuations, lateral forces may act on thefilter elements and cause the filter elements to be swivelled in theirsupporting seat. In this case, the filter elements are automaticallypartly lifted off their supporting surface, which eliminates the sealbetween filter elements and perforated plate.

Sealing could only be ensured by the filter elements in known perforatedplates being clamped against the perforated plate by additional devices.In practice, however, this is difficult to realize as gases flow throughthe region of the filters at a very high temperature (e.g. 1000 degreesC.). Also, the arrangement of additional clamping elements would renderthe apparatus very complicated, and, in particular, it must be takeninto account that the holes in the perforated plate are normallyarranged very close together, which leaves little space for thearrangement of separate clamping elements.

Finally, in the event of an undesired high rise in pressure, suchclamping elements would prevent the filter elements from being raisablefor a short time from their sealing seat, thereby enabling them toassume the function of a safety valve.

The object of the invention is to so develop an apparatus of the generickind that perfect sealing of the filter elements relative to theperforated plate is also ensured during swivel motion of the filterelements relative to the vertical center axis of the holes in theperforated plate without additional structural measures.

This object is achieved, in accordance with the invention, in anapparatus of the kind described at the beginning, by the flange-typeenlargement forming a bearing surface which lies on the surface of asphere with center point above the bearing surface and on the verticalcenter axis of the filter element, and by the hole in the perforatedplate so surrounding at a distance the filter shell of the filterelement downwardly adjoining the enlargement that the filter element canswivel over a certain angular range about the center point of thesphere.

This spherical-cap-type design of the bearing surface enables swivelmotion of the filter element about the center point of the spheresurface without breaking the sealing contact with the surroundingsupporting surface of the hole. Therefore, even in the case of slightswivel motion of the filter element, effective sealing between filterelement and perforated plate is at any rate guaranteed.

Provision may be made for an inwardly protruding annular shoulder onwhich the bearing surface of the enlargement is supported to be arrangedin the hole of the perforated plate.

It is expedient for the center point of the sphere surface to lie in theplane of the upper edge of the filter element as, in this way, thecenter point of the upper edge does not change its position relative tothe perforated plate upon swivel motion of the filter element.

Provision may be made for the supporting surface of the perforated plateon which the bearing surface of the filter element rests to likewise lieon the sphere surface. A surface-to-surface contact between bearingsurface and supporting surface which may result in a particularlyeffective sealing is then obtained.

In a modified embodiment, provision is made for the bearing surface tolinearly abut a supporting surface. To this end, the supporting surfacemay, for example, be of conical construction, but it is also possiblefor the supporting surface to be in the form of a ring-shaped knife edgeagainst which the bearing surface comes to rest.

In a preferred embodiment, stops which are preferably arranged on thebottom of the filter element are provided to delimit the swivel motionof the filter element.

For example, the stops may be formed by a vertical limiting elementwhich is stationarily arranged in the lower compartment and dipsupwardly with a play into a downwardly open cavity on a filter elementsuspended above it. Depending on the size of this play, larger orsmaller swivel motions of the filter element are possible.

It is expedient for the cavity to be formed by a blind hole in theenlarged bottom of the filter element. In this case, an elastic plugwhich surrounds the limiting element is advantageously inserted in theblind hole.

The following description of a preferred embodiment serves inconjunction with the drawing to explain the invention in greater detail.The drawing shows a partial sectional view of a perforated plate withfilter elements suspended therein.

A filter apparatus for gases comprises a closed container which isdivided by a horizontal perforated plate into a lower compartmentprovided with a gas inlet and an upper compartment provided with a gasoutlet. This container is not illustrated in the drawing; only a sectionof a horizontal perforated plate 1 is shown in which there are arrangedalongside one another several continuous holes 2 which connect the lowercompartment 3 located below the perforated plate 1 with the uppercompartment 4 located above the perforated plate. The perforated plate 1can be made, for example, of high-grade steel and extends over theentire cross-sectional area of the container which is not illustrated inthe drawing.

In the illustrated embodiment, the holes 2 comprise an inwardlyprotruding annular shoulder 5 which forms at its upper side a supportingsurface 6 for a filter element 7 suspended in each hole.

The filter elements are of cylindrical or candle-shaped design andcomprise at their lower end a closed bottom 8 and at their upper openend a radially protruding enlargement 9 whose underside forms a bearingsurface 10 supported on the supporting surface 6. This bearing surface10 lies on the surface of a sphere whose center point M lies above thebearing surface on the vertical center axis of the filter element, inthe illustrated embodiment in the plane of the upper edge 12 of thefilter element. Hence bearing surface 10 has the shape of a sphericalcap.

In the embodiment illustrated on the right in the drawing, thesupporting surface 6 of the annular shoulder 5 also has the shape of aspherical cap, and the latter also lies on the same spherical surface,i.e., the bearing surface 10 abuts the supporting surface 6 ofcomplementary configuration in a surface-to-surface manner. The hole 2and the annular shoulder 5 surround at a slight distance the filtershell 11 downwardly adjoining the enlargement, which enables swivelmotion of the filter element relative to the vertical center axis of thehole 2. During such swivel motion, the spherical-cap-shaped bearingsurface 10 slides along the supporting surface 6 of complementaryconfiguration, with surface-to-surface contact being maintained betweenthe bearing surface and the supporting surface during each possibleswivel motion.

In the illustrated embodiment, the filter element is directly supportedwith its bearing surface on the supporting surface of the annularshoulder; an annular seal which is preferably likewise ofspherical-cap-shaped configuration could also be placed between these.

In the filter element on the left in the drawing, further possibilitiesfor supporting the spherical-cap-shaped bearing surface on a modifiedsupporting surface are indicated, for example, the supporting surfacecan be of conical shape (left side of the left filter element) or thesupporting surface can be knife-edge-shaped (right side of the leftfilter element). In both cases, the spherical cap configuration of thebearing surface ensures that reliable and sealing contact is maintainedon all sides during swivel motion of the filter element.

Within the scope of the invention, a reversal is also possible, i.e., aknife-edge-shaped bearing surface on the filter element could alsocooperate in the same manner with a spherical-cap-shaped supportingsurface.

Arranged in the lower compartment 3, under each filter element on thelongitudinal center axis of the corresponding hole 2 in the perforatedplate 1 is a stationary, vertically upwardly oriented, pin-shapedlimiting element 13 which dips into a blind hole 14 in the enlargedbottom 8 of the corresponding filter element. The side walls 15 of theblind hole 14 surround the limiting element 13 at a distance from it.The limiting element 13 strikes the side wall 15 of the blind hole 14when the corresponding filter element is swivelled beyond apredetermined angular amount relative to the longitudinal axis of thecorresponding hole 2, i.e., the swivel motion of each filter element islimited by this limiting element 13. This is necessary in order to avoidmutual damaging of neighboring filter elements.

To prevent hard striking of the limiting element 13 against the sidewalls 15 of the blind hole 14, an elastic plug 16 which surrounds thelimiting element 13, as illustrated in the left filter element of thedrawing, can be inserted into the blind hole 14. In this way, anadditional restoring torque is also generated for the filter element.

The described structural measures also enable reliable sealing of thefilter elements relative to the perforated plate when the filterelements are swivelled to a slight extent relative to the vertical. Inthis case, it is not necessary to provide additional devices; inparticular, the filter elements are readily replaceable, also in thedescribed structural design, without clamping elements having to bereleased, etc.

We claim:
 1. Apparatus for filtering gases comprising a closed containerwhich is divided by a horizontal perforated plate into a lowercompartment provided with a gas inlet and an upper compartment providedwith a gas outlet, tubular or candle-shaped filter elements which aresealingly suspended in holes of the perforated plate and are supportedby a flange-type enlargement at their upper end on the perforated plate,wherein the flange-type enlargement forms a bearing surface which lieson the surface of a sphere with center point above the bearing surfaceand on the vertical center axis of the filter element, and wherein thehole in the perforated plate so surrounds at a distance the filter shellof the filter element downwardly adjoining the enlargement that thefilter element can swivel over a certain angular range about the centerpoint of the sphere, and stops provided at the bottom of the filterelement for limitation of the swivel motion of the filter element, saidstops formed by a vertical limiting element which is stationarilyarranged in the lower compartment and dips upwardly with play into adownwardly open cavity in a filter element suspended above the verticallimiting element.
 2. Apparatus according to claim 1, wherein the cavityis formed by a blind hole in the enlarged bottom of the filter element.3. Apparatus according to claim 2, wherein an elastic plug whichsurrounds the limiting element is inserted into the blind hole.